Question

I have this basic error that i can’t fix… Object reference not set to an instance of an object

I’m using asp.net mvc4 with ef

My controller

 public class PostController : Controller
    {
        private UsersContext db = new UsersContext();

        public ActionResult Index()
        {
            return View(db.Posts.ToList());
        }

        public ActionResult Create()
        {
            return View();
        }

        [HttpPost]
        public ActionResult Create(FormCollection values)
        {
            var post = new Post();
            TryUpdateModel(post);

            if(ModelState.IsValid)
            {
                var context = new UsersContext();
                var username = User.Identity.Name;
                var user = context.UserProfiles.SingleOrDefault(u => u.UserName == username);
                var userid = user.UserId;
                // var firstname = user.FirstName;

                post.UserId = userid;
                post.Date = DateTime.Now;

                db.Posts.Add(post);
                db.SaveChanges();
            }
            return View("Index");
        }

and my view :

@model IEnumerable<MyProject.Models.Post>

@{
    ViewBag.Title = "Index";
}

<h2>Index</h2>

<p>
    @Html.ActionLink("Create New", "Create")
</p>
<table>
    <tr>
        <th>
            @Html.DisplayNameFor(model => model.Content)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Date)
        </th>
        <th></th>
    </tr>

   @foreach (var item in Model) { //**line with error**

    <tr>
        <td>
                @Html.DisplayFor(modelItem => item.Content)
        </td>
        <td>
                @Html.DisplayFor(modelItem => item.Date)
        </td>
        <td>
            @Html.ActionLink("Edit", "Edit", new { id=item.PostId }) |
            @Html.ActionLink("Details", "Details", new { id=item.PostId }) |
            @Html.ActionLink("Delete", "Delete", new { id=item.PostId })
        </td>
    </tr>
}
</table>

Thanks for your help

Answer 1

You forgot to send a model to the view after the GET action in your controller. Your return statement should probably be:

    public ActionResult Create()
    {
        return View("Create", new Post());
    }

You have to supply something for the model or it will be null in the view.

You’ll probably have the same problem with your POST method as well, which returns:

return View("Index");

Rather than doing that, you should probably just redirect to the Index action:

return RedirectToAction("Index");

Also, you would only want to do that on success – if the model state wasn’t valid, you probably want to go back to the create screen to show the errors. So your post action would end up something like this:

   [HttpPost]
    public ActionResult Create(FormCollection values)
    {
        var post = new Post();
        TryUpdateModel(post);

        if(ModelState.IsValid)
        {
            var context = new UsersContext();
            var username = User.Identity.Name;
            var user = context.UserProfiles.SingleOrDefault(u => u.UserName == username);
            var userid = user.UserId;
            // var firstname = user.FirstName;

            post.UserId = userid;
            post.Date = DateTime.Now;

            db.Posts.Add(post);
            db.SaveChanges();

            return RedirectToAction("Index");
        }

        return View("Create", post);
    }